“It will be observed, however, that in the former case the ammoniacal salts were top-dressed, but in the latter they were drilled at the time of sowing the seed; and it will be remembered that in 1845 the result was better _as to corn_ on plot 9, where the salts were sown earlier, than on plot 10, where the top-dressing extended far into the spring. We have had several direct instances of this kind in our experience, and we would give it as a suggestion, in most cases applicable, that manures for wheat, and especially ammoniacal ones, should be applied before or at the time the seed is sown; for, although the apparent luxuriance of the crop is greater, and the produce of straw really heavier, by spring rather than autumn sowings of Peruvian guano and other ammoniacal manures, yet we believe that that of the _corn_ will not be increased in an equivalent degree. Indeed, the success of the crop undoubtedly depends very materially on the progress of the underground growth during the winter months; and this again, other things being equal, upon the quantity of available nitrogenous constituents within the soil, without a liberal provision of which, the range of the fibrous feeders of the plant will not be such, as to take up the minerals which the soil is competent to supply, and in such quantity as will be required during the after progress of the plant for its healthy and favorable growth.” These remarks are very suggestive and deserve special attention. “The next result to be noticed,” continue Messrs. Lawes and Gilbert, “is that obtained on plot 6, now also divided into two equal portions designated respectively 6_a_ and 6_b_. Plot No. 6 had for the crop of 1844, superphosphate of lime and the phosphate of magnesia manure, and for that of 1845, superphosphate of lime, rape-cake, and ammoniacal salts. For this, the third season, it was devoted to the trial of the wheat-manure manufactured under the sanction of Professor Liebig, and patented in this country. “Upon plots 6_a_, four cwts. per acre of the patent wheat-manure were used, which gave 20¼ bushels, or rather more than two bushels beyond the produce of the unmanured plot; but as the manure contained, besides the minerals peculiar to it, some nitrogenous compounds, giving off a very perceptible odor of ammonia, some, at least, of the increase would be due to that substance. On plot 6_b_, however, the further addition of one cwt. each of sulphate and muriate of ammonia to this so-called ‘Mineral Manure,’ gives a produce of 29¼ bushels. In other words, the addition of ammoniacal salt, to Liebig’s mineral manure has increased the produce by very nearly 9 bushels per acre beyond that of the mineral manure alone, whilst the increase obtained over the unmanured plot, by 14 tons of farm-yard manure, was only 9¼ bushels! The following table gives the results of the experiments the _fourth_ year, 1846-7. Experiments at Rothamsted on the Growth of Wheat, Year After Year, on the Same Land.